tectorigenin and kakkalide

This study investigated the metabolic fate of kakkalide (irisolidone 7-xylosylglucoside), a major isoflavone found in extracts of Pueraria lobata flowers, and in rat urine, bile, and feces. Using HPLC/UV or LC/MS/MS methods, seven metabolites, tectorigenin-7-O-glucuronide, tectorigenin-7-O-sulfate, tectorigenin-4'-O-sulfate, 6-OH biochanin A-glucuronide, irisolidone-7-O-glucuronide, tectorigenin, and irisolidone were identified in rat urine after oral administration of kakkalide. Furthermore, irisolidone-7-O-glucuronide was found in bile, and irisolidone and kakkalide were found in feces. An HPLC/UV method for simultaneous quantification of all the metabolites and kakkalide in urine, bile, and feces was developed using daidzein or apigenin as the internal standard. Over a 72-h period, 13.2 ± 2.8 % of the kakkalide was excreted as seven metabolites in urine. Over the same time period, irisolidone-7-O-glucuronide excretion in bile accounted for 3.8 ± 1.1 % of the dose, while kakkalide and irisolidone excretion in feces accounted for 2.1 ± 0.7 % and 0.7 ± 0.1 % of the dose, respectively. The results indicate that urine is the primary route of kakkalide elimination in vivo and that extensive metabolism may be one of the reasons for the low bioavailability of kakkalide.

Topics: Administration, Oral; Animals; Bile; Chromatography, High Pressure Liquid; Chromatography, Liquid; Feces; Flavonoids; Glycosides; Isoflavones; Male; Pueraria; Rats; Rats, Wistar; Tandem Mass Spectrometry

To understand the relationship between the metabolism and estrogenic activity of kakkalide and tectoridin, main isoflavones in the flower of Pueraria thunbergiana (family Leguminosae), these isoflavones and their metabolites by human intestinal microflora as well as their estrogenic effects were investigated. All human fecal specimens metabolized kakkalide and tectoridin. All isolated kakkalide-hydrolyzing intestinal bacteria also hydrolyzed kakkalide and tectoridin to irisolidone and tectorigenin, respectively. When the estrogenic effects of kakkalide and tectoridin were compared with those of their metabolites irisolidone and tectorigenin, the metabolites more potently increased proliferation of MCF-7 cells than kakkalide and tectoridin. These metabolites also potently induced estrogen-response c-fos and pS2 mRNA expression. These results suggest that kakkalide and tectoridin may be metabolized mainly to irisolidone and tectorigenin, respectively, by intestinal microflora in the intestines, and which may be subsequently absorbed into the blood where they can express their estrogenic effect.

Topics: Adult; Bifidobacterium; Cell Line, Tumor; Cell Proliferation; Feces; Flavonoids; Flowers; Glycosides; Humans; Intestines; Isoflavones; Male; Phytoestrogens; Pueraria; Substrate Specificity; Xylosidases; Young Adult